Barone, Michael
National Journal, 1992
Buku Referensi
Althen, Gery
Intercultural Press, 2003
Buku Teks
Hombs, Mary Ellen
ABC-Clio, 1990
Buku Teks
Polsby, Nelson W.
Charles Scribner's Sons, 1980
Buku Teks
Polsby, Nelson W.
Charles Scribner`s Sons, 1964
Buku Teks